Nuts and bolts are considered COTS items: Commodity Off The Shelf. They are not particular to e.g. the Falcon 9 or Starship. The word Commodity is important here - changing suppliers is relatively simple and there are standards that can be adhered to (but need to be checked, remember CSR-7).

Things like screens and chips are less of a commodity than are aerospace-grade bolts, but if I'm not mistaken many of these components are shared with another Musk company that designs and manufactures automobiles - so they have commodity of scale and a long track record, plus many realworld users to uncover bugs. It might not be the exact same component, but much is shared. One prominent example that was stated explicitly recently was the actuator motors for the Starship flaps - right out of a Tesla.